Method of coating yarn

ABSTRACT

A yarn texturing and coating operation where a traveling yarn is air bulked or textured and coated with liquid prior to collection into a wound package. The coating apparatus includes: adjacent rotatably mounted members each having an external groove circling its axis of rotation; means for advancing the textured yarn between the members and through a portion of each of the grooves; means for rotating the members together in opposite directions to move the walls of the grooves at a speed less than the speed of and in the same direction as the textured yarn advanced through the grooves; and means for supplying a liquid to the grooves in advance of the yarn. The moving walls of the grooves move the liquid into contact with the yarn to effect a coating thereon as it travels through the grooves.

United States Patent Benson 1 Jan. 28, 1975 METHOD OF COATING YARN 3.338.738 8/1967 Lindemann 117/115 3,488,670 l/l970 Benson 28/l.4 [75] Inventor: Gustav E. Benson, Edgewood, R.l. 15087950 W970 Marmcchz" 7/72 73 Assigneez owens corning bu-3|as 3,749,055 7/1973 Benson ll8/234 Corporation Primary Examiner-Michael Sofocleous [22] 1973 Attorney, Agent, or Firm-Carl G. Staelin; John W. [21] Appl. No.: 348,429 Overman; Ronald C. Hudgens Related U.S. Application Data [62] Division of Ser. No. 167,399,1uly 29, I971, Pat. No. [57] ABSTRACT A yarn texturing and coating operation where a traveling yarn is air bulked or textured and coated with liq- [52] U.S. Cl. 117/11] R, ll7/l 11 B, ll7/l l5, uid prior to collection into a wound package. The 118/234, 28/l.4, 28/75 WT coating apparatus includes: adjacent rotatably [51} .Int. Cl D02g 3/24, D02g l/l6 mounted members each having an external groove cir- [58] Field of Search ll7/l ll R, 111 H, 11] B, cling its axis of rotation; means for advancing the texll7/1 l5; ll8/2l6, 234, 258, 405, 419, DIG. tured yarn between the members and through a por- 20; 28/28, 1.4, 75 R, 75 WT tion of each of the grooves; means for rotating the members together in opposite directions to move the [56] References Cited walls of the grooves at a speed less than the speed of UNITED STATES PATENTS and in the same direction as the textured yarn ad- 2 384 542 9/1945 Fruth at a H7 15 vanced through the grooves; and means for supplying 247s 230 8/1949 BOLHCI LIT 221... 28/28 a quid to the grooves in advance of Y The 215473047 4/1951 Saums et al 117/113 moving Walls Of the grooves move the liquid into 2.723.215 ll/l955 Biefeld et al.... 154/91 Contact with the yarn to effect a coating thereon as it 2,835,221 5/l958 Slayter et al.... HIS/DIG. 20 travels through the grooves. 3,117,883 l/l964 Fox 118/234 3,233,059 3/l966 Stobierski 117/115 3 ClalmS, 6 Drawing Flgures 1% V-OPHAT/QV/M /27 I Mr? P47 l PUMP.

07%?47/04/41 r -744E510" 1/71/5 )flfl/VPfl7//""\ PATENTEDJAN28I975 3,862,853.

SHEET 2 OF 3 Fig-i PATENIE JAN28 ms SHEET 3 0r 3 IIIHI METHOD OF COATING YARN This is a division, of application Ser. No. 167,399, filed July 29, 1971, now U.S. Pat. No. 3,749,055.

BACKGROUND OF THE INVENTION Textile yarns commonly receive liquid treatments for protection, for desired yarn properties and for other purposes. Yet often prior art apparatus for applying liquid treatment to traveling yarns has not been adequate.

Uniform and continuous liquid yarn treatment is especially vexing in processes advancing yarn at high speeds. Liquid applied to a yarn nonuniformly and discontinuously results in a yarn with untreated or nonuniformly treated portions.

Liquids such as coating or sizing liquids commonly hold trapped gases such as air in the form of bubbles. Prior high speed yarn treating apparatus and processes do not allow gas to escape beforeyarn contacts the liquid. Hence, with prior apparatus and methods liquid with trapped gas bubbles commonly comes into contact with traveling yarn. Escape of gas from liquid upon or after contact with yarn can leave unsized or untreated portions along the yarns length. The result is especially severe when the liquid contains color; a nonuniformly colored yarn ensues.

- Then too, apparatus for effecting liquid treatments to speeding yarn often effect an uneven treatment above the yarns circumference.

SUMMARY OF THE INVENTION An object of the invention is improved apparatus for and method of treating a traveling yarn with flowable material, especially at higher yarn speeds.

Another object of the invention is apparatus for and method of uniformly transferring a liquid to a traveling yarn.

Another object of the invention is apparatus for and method of transferring a controlled amount of liquid containing pigment to traveling yarn to effect uniform color distribution along the length of the yarn, especially at higher yarn speeds.

Yet another object of the invention is apparatus for and method of treating a traveling yarn with a liquid on more than one side of the yarn.

These and other objects are attained by apparatus advancing yarn through a groove in a surface, advancing the surface in a direction of yarn travel to move the walls of the groove at a speed less than the speed of the advancing yarn and supplying flowable material to the groove in advance of the yarn traveling in the groove.

Other objects and advantages will become apparent as the invention is hereafter described in more detail with reference made to the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of apparatus for treating glass yarn according to the principles of the invention in a yarn bulking process.

FIG. 2 is a simplified view of the drive mechanism for the yarn feed and withdrawal apparatus shown in FIG. 1.

FIG. 3 is an enlarged front elevation view of the applicator shown in FIG. 1 for applying flowable material to advancing yarn.

FIG. 4 is an enlarged side elevation view partly in section of the applicator shown in FIG. 3. FIG. 4 more clearly shows the transfer rolls and the drive mechanism for the rolls.

FIG. 5 is an enlarged front elevation view, partly in section, of a portion of one of the transfer rolls shown in FIGS. 1, 3 and 4. FIG. 5 more clearly shows the relationship between supply of flowa ble material from a supply tube and transfer roll.

FIG. 6 is a partial cross section view showing part of i the transfer roll of FIG. 5 with a textured yarn in the circumferential groove of the roll.

DESCRIPTION OF THE PREFERRED EMBODIMENTS While the apparatus and method of the invention are especially useful in processing twisted multifilament linear textile element such as continuous or discontinuous filament glass yarn, the invention finds advantageous use in processing untwisted multifilament linear textile elements such as glass strand. One can use multifllament textile elements or organic filaments, such as nylon,-rayon, polyester and the like. Additionally, the invention is useful in processing composite multifilament linear elements, such as elements including both glass fibers and other fibers. Hence, the term yarn as used in the specification and claims includes any bundie of filaments (continuous or discontinuous) that either has twist or does not have twist. The term also includes textured and untextured bundle of filaments.

FIG. 1 show apparatus for producing a textured glass yarn at high yarn speeds. The apparatus includes yarn texturing, yarn sizing and yarn collecting portions.

A supply package 10 on a platform 12 supplies continuous filament glass 'yarn 14 to the yarn texturing apparatus through a pigtail 16 above the package 10. The yarn texturing apparatus includes yarn feed and withdrawal apparatus 18 and a fluid yarn texturing nozzle or jet 20, which has an entrance 22 and an exit 24.

The jet creates a yarn texturing zone of fluid agitation as it releases fluid from its exit 24; fluid in thezone bulks or textures yarn leaving the jet 20. A supply line 26 carries texturing fluid, normally a gas such as air, under pressure to the interior of the jet 20 from a source of such fluid under pressure. The source can be a commercial air compressor.

Fluid texturingjets are generally known in the textile art. Yet in practice it has been especially useful to use fluid jets like those disclosed in US. Pat. Nos. 3,328,863 and 3,402,445.

The yarn feed and withdrawal apparatus 18 handles yarn to and from the jet 20 and includes a pair of spaced apart cooperating double diameter feed and withdrawal rolls 28 and 30 carried by shafts 32 and 34 respectively. These shafts are rotatably mounted on a housing 36.

As more clearly seen in FIG. 2, an electric motor 38, through a drive arrangement, rotates the rollers 28 and 30 together in the same direction and at the same angular speeds. belt 40 connects a pulley 42 on the output shaft 44 of the motor-38 with a pulley 46 on the shaft 32. A second belt 48 connects another pulley (behind pulley 46) on the shaft 32 with a pulley 50 on the shaft 34. As shown in FIGS. 1 and 2 the rolls 28 and 30 move in a clockwise direction.

Because it is important that the peripheral speed of the rollers 28 and 30 be the same at corresponding points on their peripheries. the rolls are normally identical in size. If the rolls are different in size, one must modify the drive arrangement to effect the same peripheral speed for each of the rolls.

Assuming the rolls 28 and 30 have identical dimensions, each of these rollers includes a first cylindrical section 52 having a diameter D and a second coaxially arranged cylindrical section 54 having a diameter 11" that is smaller in dimension than the diameter D." The cylindrical sections 52 of D diameter feed the untextured yarn 14 to the entrance 22 of the fluid texturing jet 20; the cylindrical sections 54 of :1 diameter draw a textured 14 from the exit 24 of the fluid jet 20. The rolls 28 and 30 feed the yarn 14 to the fluid jet 20 at a faster linear speed than the textured or bulked yarn 14' is withdrawn from the fluid jet 20. Thus, the rolls 28 and 30 provide an amount of over-feed" to the jet 20 and the ratio of the diameters D/d" determines the overfeed.

With the yarn feed and withdrawal apparatus 18 located with the jet 20 as shown in FIG. 1, the feed and withdrawal rolls 28 and 30 advance the yarn 14 from its supply package to travel about and between the peripheral surfaces of the larger and first cylindrical sections 52 on each of the feed and take up rollers 28 and 30 and then into the entrance 22 of the fluid jet 20. The second cylindrical section 54 at each of the rolls 28 and 30 withdraws the yarn from the fluid jet as the textured yarn 14'. The apparatus locates the second cylindrical section 54 of the roll 30 in a relation to the outlet 24 of the fluid jet 20 so as abruptly to remove the textured yarn 14' in a lateral direction from its path through the fluid jet 20.

The yarn winds around and between the peripheral surfaces of the cylindrical sections 52 and 54 a number of times sufficient to provide enough engagement with the surfaces to prevent slippage as the yarn is being fed to and withdrawn from the fluid jet 20. In practice it has been determined that approximately 4-6 times around and between each of the paths of the cylindrical sections 52 and 54 is sufficient to prevent yarn slippage.

In practice it is possible to withdraw the yarn 14 from the jet 20 at speeds up to 3,000 feet-per-minute and faster.

From the yarn texturing apparatus the textured yarn l4 advances downwardly across liquid transfer rolls 56 and 58 of a sizing applicator 60 for a sizing treatment. As the yarn 14 travels across the surfaces of the rolls 56 and 58, liquid sizing in metered amounts transfers to it. The sizing applicator 60 as shown effects transfer of liquid sizing to opposite sides of the textured yarn 14.

The liquid sizing can be any suitable composition. For example, one can use conventional starch, gelatin or resin based sizing compositions. Other coatings 'can be applied by the applicator 60 such as flowable material of plastic composition, either thermoplastic or thermosetting. The flowable material can be a hot melt. It is possible to apply a flowable material having pigment to the yarn 14.

From the sizing applicator 60 the textured yarn 14 advances to yarn collecting apparatus 66. As shown, the yarn 14 moves from the applicator 60 downwardly to a yarn guide roller 68 rotatably mounted on the free end of a pivotally mounted yarn tension sensing arm 70. This arm comprises part of the yarn collecting apparatus 66, which is illustrated as a constant tension yarn take-up device.

Constant tension yarn take-up devices are commercially available. Such devices include a yarn tension sensing mechanism comprising the arm and associated electrical-mechanical controls that combine to vary the speed of the mandrel upon which a yarn package builds in accordance with variations in the tension of a linear element (textured yarn 14) being wound.

As shown, the textured yarn l4 advances from the guide roller 68 to be wound as a package 72 on a mandrel 74. An electrical motor 76 drives the mandrel 74. A yarn traversing mechanism 78, also forming part of the yarn collecting apparatus 66, reciprocates the textured yarn 14' lengthwise of the package'72 as the yarn 14 winds onto the package 72.

FIGS. 3 and 4 more clearly show the sizing applicator 60, which includes an enclosure 90, the liquid transfer rolls 56 and 58 and associated liquid supply tubes 92 and 94 for supplying liquid to the rolls 56 and 58 respectively.

As seen in FIG. 4 shafts 96 and 98 are rotatably mounted on the enclosure these shafts carry the rolls 56 and 58 respectively.

The liquid transfer rolls 56 and 58 each include a cylindrical liquid transfer portion and a tapered yarn guide joined to the liquid transfer portion at one end. The roll 56 includes cylindrical liquid transfer portion 100 and a conical guide 102; the roll 58 includes cylindrical liquid transfer portion 104 and a conical guide 106. As illustrated the cylindrical liquid transfer portions 100 and 104 are the same size. The conical guides 102 and 106 are alike except for their smaller end configurations. The conical guide 102 includes a yarn retaining end configuration at its smaller end. As shown a generally spherically shaped yarn retaining knob 108 is at the smaller end of the guide 102. The knob 108 is larger than the adjacent tapering cross section of the conical yarn guide 102.

The guides 102 and 106 extend in diminishing cross section from their base ends at the cylindrical portions 100 and 104. The conical guides 102 and 106 extend coaxially from the corresponding ends of their cylindrical liquid transfer portions, i.e., portions 100 and 104 respectively. The base ends of the guides 102 and 106 have diameters that are the same size as the diameter of their respective cylindrical portions.

ln treating glass yarn the rolls 56 and 58 are normally made of material with reduced effects of abrasion both to the yarn and by the yarn. One can use materials such as tungsten carbide, brass and graphite. Tungsten carbide is preferred because of its higher resistence to abrasion by the yarn.

The axial or lengthwise surfaces of the cylindrical liquid transfer portions 100 and 104 have identical circumferential grooves. The portion 100 has a groove 110 defined by walls 111; the portion 104 has a groove 112 defined by walls 113. Each of these grooves encircle its respective portion in a plane substantially perpendicular to the axis of rotation of the portion. The location of the rolls 56 and 58 on the enclosure 90 aligns the grooves 110 and 112.

A motor 114 and gear trains within the enclosure 90 the rolls 56 and 58 together in opposite directions at the same angular speed. As shown the motor 114 rotates a spur gear 116 fixed on its output shaft 118. The gear 116 peripherally engages a spur gear 120 fixed on the shaft 98. Also on the shaft 98 is a spur gear 122 spaced from the spur gear 120; the gear 122 engages a spur gear 124 on the shaft 96. The gears 122 and 124 are the same size; hence the rolls 56 and 58 (shafts 96 and 98) rotate in opposite directions with the same an gular speed when driven by the motor 114.

The motor 114 rotates the rolls 56 and 58 to move the walls 111 and 113 of the grooves 110 and 112 at speeds less than the speed of the advancing yarn l4. Normally the motor 114 rotates the rolls 56 and 58 from 5 to 500 rpms. Since the rolls are usually fairly small, e.g. 1 inch in diameter, the surface speed of the grooves 110 and 112 are slow compared with the speed of the yarn processed by the apparatus shown in FIG.

The dashed line path denoted by Operational Yarn Path in FIGS. 3 and 4 more clearly shows the path of yarn travel across the sizing applicator 60. Advancing yarn turns on the cylindrical liquid transfer portion 100 of the roll 56 in the groove 110 over an arc defined by angle A; angle A is normally not larger than 30 when glass yarn is used. Yarn leaves the groove 110 to travel between the rolls 56 and 58 along a path tangent to both portions 100 and 104. Yarn turns a small amount on the cylindrical portion 104 of the roll 58 in the groove 112. The angle B indicates the amount of yarn turn on the cylindrical portion 104. Angle B is the angle form between the tangent line between the portions 100 and 104 and the path of yarn withdrawal from the roll 58. This angle is normally from 5 to The yarn path shown in FIGS. 1, 3 and 4 is the type of yarn path used for faster yarn processing speeds. For higher processing speeds the angles A and B are smaller to reduce broken filaments caused from engagement between the rolls 56 and 58 and traveling yarn.

It is possible, and perhaps desirable under certain circumstances, to turn yarn equal amounts on the rolls 56 and 58. i

In the yarn turning regions of the rolls 56 and 58 in grooves 110 and 112 respectively, the yarn and the rolls are moving in the same direction. From FIG. 3 it can be seen that yarn approaches the roll 56 from the left; the roll 56 is rotating in a counterclockwise direction. Yarn leaves the roll 58 from the right hand side; the roll 58 is rotating in a clockwise direction.

Because the walls 111 and 113 of the grooves 110 and 112 move at a speed less the speed of the advancing yarn 14', the yarn l4 slides across the walls 111 and 113 of the grooves 110 and 112.

The applicator 60 coats or treats the yarn 14' with a measured amount of liquid as the yarn turns on the cylindrical portions 100 and 104 in the grooves 110 and 112. As shown in FIG. 3 a pump 126 supplies a controlled amount of liquid to the outlets of the tubes 92 and 94 through supply lines 127 and 128 respectively. To supply liquid to the yarn 14' in the groove 110 and 112 the supply tubes 92 and 94 have their outlets circumferentially spaced from the Zone of yarn engagement for their respective rolls in a direction opposite to the direction of roll rotation. Hence, the tubes supply a metered amount of liquid to the grooves in advance of the yarn 14 in the grooves. Also, the tubes 92 and 94 terminate adjacent to the periphery of the cylindrical portions 100 and 104 and align with the grooves 110 and 112 respectively. Preferably, the tubes 92 and 94 terminate in the grooves 110 and 112 respectively. The tubes 92 and 94 are shown terminating in the grooves 110 and 112 and somewhat tapered at their terminating regions.

The moving walls 111 and 113 of the grooves and 112 carry liquid released from the exit of the supply tubes 92 and 94 to the liquid transfer zones within these grooves, i.e., where the yarn 14 turns on the rolls 56 and 58.

FIG. 5 more clearly shows the liquid supply and transfer zone for the roll 56. The moving walls 111 of the groove 110 carry liquid released from the supply tube 92 in advance of the yarn in the groove. As the walls 111 carry the liquid to the yarn, trapped gas in the liquid can escape and the liquid can flow together when voids are present in the liquid 130 released from the tube.

Normally the applicator 60 continuously treats the yarn traveling across it. Hence, it is usual to provide liquid continuously to the yarn 14 at both rolls. Of course the rate of supply will vary for different conditions such as yarn denier and yarn processing speed. The type of coating or sizing and their viscosities can also effect the liquid supply rate needed. The applicator 60 may be used to fully impregnate a yarn. FIG. 6 shows the roll 56 partially impregnating the yarn l4.

Usually the grooves 110 and 112 reduce in cross section from larger cross sections at their mouths or entrance regions at the surface of the rolls to smaller cross sections at their bottom regions. FIG. 6 shows the cross section of the groove 110. Because the grooves 110 and 112 are identical, FIG. 6 is also representative of groove 112.

For improved coating action the cross sectional areas of the grooves 110 and 112 at their bottom regions are less than the cross sectional area of yarn traveling through the grooves. Thus the coating liquid and yarn are brought into intimate contact.

FIG. 6 shows a cross sectional view of the yarn 14' in the groove 110 of the roll 56. The bottom wall region of the groove is curved with a radius smaller than the radius of the yarn 14.

As the yarn 14' travels through the grooves 110 and 112 in contact with the liquid 130, movement of the yarn 14 at a higher speed adjacent to the slower moving walls of the grooves establishes shearing stresses in the liquid; these stresses tend to dissipate gas still entrained in the liquid and tend to distribute the liquid in the grooves to substantially reduce discontinuity in the supply of liquid to the yarn 14' as it travels through the grooves 110 and 112.

In practice good results have been obtained when the surface speed and the rollers 56 and 58 are substantially less than the yarn speed.

An arrangement that turns advancing yarn in the grooves 110 and 112 on the rolls 56 and 58 is preferred, especially at high yarn speeds. It is possible to advance yarn, e.g. the yarn 14', between the rolls 56 and 58 and through a portion of the grooves 110 and 112 without turning the yarn on the rolls. In such an arrangement the yarn path across the rolls would be essentially a straight path vis-a-vis a curved path as shown in FIGS. 1, 3 and 4.

At higher yarn speeds yarn advancing along a straight path tends to vibrate, which adversely affects treatment of the yarn advancing across the rolls 56 and 58 in their respective grooves. When an arrangement turns the yarn on the rolls 56 and 58 in grooves 110 and 112, such turning establishes sufficient tension in the yarn to urge the yarn towards the bottom of the grooves, which discourages yarn vibration. More uniform yarn contact with liquid supplied to it in the groove ensues.

In operation apparatus of the invention advances the yarn 14' through a groove in a surface moving in the direction of yarn travel sufficiently to move the walls of the groove at a speed less than the speed of the yarn 14'. Flowable material, such as a liquid sizing, is supplied in controlled amounts to the groove in advance of the yarn in the groove. The moving walls of the groove carry the metered amounts of flowable material into contact with the yarn in the groove.

There are times when an operator does not desire to treat a yarn with the applicator 60, e.g. at machine start-up. During these times an operator can position yarn travel over and between the tapered guides 102 and 106 as illustrated by dashed lines in FIGJ4 denoted Auxiliary Yarn Path.

The yarn travels in the hollow formed by the tapering cross section of the conical guide 102 and the retaining knob 108. It is possible to use a yarn retaining knob on the small end of the conical guide 106 too.

When an operator is ready to treat the yarn, he merely moves the yarn along the conical guides 102 and 106 and over their-larger ends into the grooves 110 and 112. Suitable means such as an air actuated piston and cylinder can be used to move the sizing applicator to effect movement of yarn from the Auxiliary Yarn Path into the grooves 110 and 112.

While the applicator 60 shows the rolls 56 and 58 spaced apart on opposite sides of the yarn 14', there may be times when the rolls 56 and 58 may be positioned to effect a treatment on a yarns circumference I at other zones. For example the rolls might be placed on axes extending in normal directions. Then too, under certain conditions it may be advantages to mount the rolls 56 and 58 with the circumferential surfaces of the cylindrical portions 100 and 104 in contact. The walls 111 and 113 of the grooves 110 and 112 would form a passageway at the region of contact between the portions 100 and 104.

I claim:

1. The method of treating yarn with liquid coating material comprising:

advancing a yarn through a first external groove located at one side of the yarn and encircling the axis of rotation of a first rotatably mounted member; rotating the first member to move the walls of the groove in the direction of yarn movement at a speed less than the speed of the yarn; advancing the yarn after it has left the first groove through a second external groove located at the opposite side of the yarn and encircling the axis of rotation of a second rotatably mounted member; rotating the second member to move the walls of the second groove in the direction of yarn movement at a speed less than the speed of the yarn; and supplying a stream of liquid coating material to each of the grooves in advance of the yarn so that the walls of each of the grooves moves the supplied liquid coating material into contact with the yarn to effect a uniform coating of the yarn. 2. The-method of coating a yarn comprising: advancing a yarn along a path extending between two adjacent cylindrically shaped rotatable members each having a circumferential groove encircling its axis of rotation in a plane substantially normal to such axis and being generally in alignment with the other circumferential groove, the path of the yarn extending through a portion of each of the grooves; rotating the members together in opposite directions to move the walls of the grooves at a speed less than the speed of and in the same direction as advancing yarn traveling through the grooves; and supplying a stream of liquid coating material to the grooves in advance of the yarn, said liquid being moved by walls of the grooves into contact with the yarn traveling through the grooves to effect a uniform coating thereof. 3. The method of claim 2 wherein the step of supplying the liquid coating material to the grooves comprises discharging said liquid from a tube having its outlet at the respective groove. 

1. THE METHOD OF TREATING YARN WITH LIQUID COATING MATERIAL COMPRISING: ADVANCING A YARN THROUGH A FIRST EXTERNAL GROOVE LOCATED AT ONE SIDE OF THE YARN AND ENCIRCLING THE AXIS OF ROTATION OF A FIRST ROTATABLY MOUNTED MEMBER; ROTATING THE FIRST MEMBER TO MOVE THE WALLS OF THE GROOVE IN THE DIRECTION OF YARN MOVEMENT AT A SPEED LESS THAN THE SPEED OF THE YARN; ADVANCING THE YARN AFTER IT HAS LEFT THE FIRST GROOVE THROUGH ASECOND EXTERNAL GROOVE LOCATED AT THE OPPOSITE SIDE OF THE YARN AND ENCIRCLING THE AXIS OF ROTATION OF A SECOND ROTATABLY MOUNTED MEMBER: ROTATING THE SECOND MEMBER TO MOVE THE WALLS OF THE SECOND GROOVE IN THE DIRECTION OF YARN MOVEMENT AT A SPEED LESS THAN THE SPEED OF THE YARN; AND SUPPLYING A STREAM OF LIQUID COATING MATERIAL TO EACH OF THE GROOVES IN ADVANCE OF THE YARN SO THAT THE WALLA OF EACH OF THE GROOVES MOOVES THE SUPPLIED LIQUID COATING MATERIAL INTO CONTACT WITH THE YARN TO EFFECT A UNIFORM COATING OF THE YARN.
 2. The method of coating a yarn comprising: advancing a yarn along a path extending between two adjacent cylindrically shaped rotatable members each having a circumferential groove encircling its axis of rotation in a plane substantially normal to such axis and being generally in alignment with the other circumferential groove, the path of the yarn extending through a portion of each of the grooves; rotating the members together in opposite directions to move the walls of the grooves at a speed less than the speed of and in the same direction as advancing yarn traveling through the grooves; and supplying a stream of liquid coating material to the grooves in advance of the yarn, said liquid being moved by walls of the grooves into contact with the yarn traveling through the grooves to effect a uniform coating thereof.
 3. The method of claim 2 wherein the step of supplying the liquid coating material to the grooves comprises discharging said liquid from a tube having its outlet at the respective groove. 